The synthesis and antirhinovirus activity of syn and anti isomers of 6-[[(hydroxyimino)phenyl]methyl]-1-[(1-methylethyl)sulfonyl]-1H-benzimidazol-2-amine (4 and 5) are reported. The structural assignments of 4 and 5 are based upon 13C NMR spectra of both isomers and also X-ray analysis of 5. The anti-isomer 5 was more potent than the syn-isomer 4 when compared as an inhibitor of rhinovirus multiplication in vitro. Both isomers inhibited multiplication of 15 different serotypes of rhinovirus.
The acidic aqueous degradation of the 7alpha-aminophenylglycinamido-containing cephalosporin cephalexin (1a) has been examined. Two major degradation products have been isolated and characterized: 3-formyl-3,6-dihydro-6-phenyl-2.5(1H,4H)-pyrazinedione (5) and 3-hydroxy-4-methyl-2(5H)-thiophenone (6). By carrying out the reaction in 18O-enriched H2O, the intramolecular nature of the cephalexin degradation has been demonstrated.
The chemical reactivity of 3-chloro-3-cephems was found to be similar to that of the correspondingly substituted 7-aminocephalosporanic acids and 12-13 times greater than that of the correspondingly substituted 7-aminode-acetoxycephalosporanic acids. Cefaclor, 7-(D-2-amino-2-phenylacetamido)-3-chloro-3-cephem-4-carboxylic acid, was found to undergo intramolecular nucleophilic attack at the beta-lactam. Loss of chlorine from 3-chloro-3-cephem may be a general reaction subsequent to beta-lactam opening.
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